Magnetoelectric pick-up device for stringed musical instruments



Patented 10, 1939 HMQSIIIHIIOI mum rick-or navics me more men,

New York. 8.1., aslisnor tionelli'ewl'erk M W 1., 1m, Sclall'io. 173,158

2. Chill- ((3. u-rie) The present invention relates to stringed musical instruments such as the guitar. banio. manparticularly to a plifled and transformed into sounds inginpitchandqualitytothesoundsproduoed ill by the vibrations of the string The-principal nhiect of the t inven istoprovideinastringfl musica 1;, an improved type of tric rick-up unit which will faithfully-and accurately reprol duce the haracterist tones of the instrument. Another object of the invention is to provide in a stringed musical instrument, a pick-up unit which is adjustable for each string of the instrument. A further object of the invention is to 9 provide in a stringed musieal'instrument havg5 therebetween, to compensate for the ordinary as those skilled in the art to which the present invention relates.

with the above and other objects in view. the

presentinvention consists of the novel features a of construction and arrangement of parts herein- 49 after set forth and illustrated in the'accompanying drawing wherein there is shown the preferred embodiment of my invention.

In the accompanying drawing which forms an integral part of this specification.

Fig. 1 is, a' top plan view of the body portion of a stringed musical instrument showing theembodiment of my invention together with an a'mpifying circuit associated therewith;

a instrument taken on the line 2-: or mg. a; and Fig. 3 is an enlarged fragmentary sectional view of the instrument taken on the line H of Fig. 1.

Referring now reference ch is preferably constructed of non-resonant matea rial such as metal or hard wood of substantial thickness, for the present invention contemplates the reproduction of the tones produced solely by the vibrations of the strings without any resonant effects which may be produced by the body 1 of the instrument. Extending from the body IQ,

in the conventional manner, is the neck of the instrument I I which may be 'attached to the body or may be constructed integral therewith. The upper side of the neck [I forms a fingerboard which is provided with spaced frets l2. Strings I 3, which are preferably made of magnetic material and which are, in the conventional practice, of unequal diameters, are tensioned over the body and neck of the instrument in parallel so arrangement, and lie in substantially a common plane. 'lhe strings II pass over 'a bridge ll which is secured to the upper side of the body It and is situated toward the outer end thereof. and over a similar bridge (not shown) on the go fingerboard, situated near the outer end of the neck H. The strings I! are secured at one end to a tail-piece Ii and at the other end they are engaged by keys or pegs (not shown) which are strings are in this manner ada to be inanually plucked or otherwise mani ated by the player to produce the d vibrations.

The pick-u unit which. designated in general by numer i ll, comprises a permanent magas net I! of U-shape or horse-shoe design. Mounted over one of the poles of the magnet I1 is an angular plate II which is constructed of magnetic material having a lesser degree of hardness than the magnet I'I to make it adaptable for so tapping in order to receive the threaded coremembers which will be referred to hereinafter.

The magnet l1 and the anguar pole-plate II are together attached to an elongated supporting bar or bracket II by means of suitable studs or 6 bolts 2.. The pick-up unit is mounted within the interior of the body ll by means of suitable studs or bolts 2i which project upwardly from the ends of the supporting bar or bracket is and extend through openings in the upper side of the 50 body. Nuts 22 are threaded over the outer ends of the bolts ii for securing the unit It to the upper side of the body.

The pick-up unit includes a plurality of coremembers v 23 of magnetic material which are lsvldedwithan opening whereby to permit from the upper sideof the threaded into the pole-plate i8 and project upwardly, the upper ends being spaced directly bdow the strings H as illustrated in Figs. 2 and 3 of the drawing. The core-members it are threaded into the pole-plate ii? to permit of their adjustment relative to the strings in order to obtain the proper spacing therebetween, and are preierably provided with screw heads-24 so that they may be readily adjusted with a screw-driver. The pick-up unit also includes a coil 25 of suitable wire which is preferably wound on a spool 26 formed of suitable insulating material. The spool 26 is adapted to he supported on the pole plate it and surrounds the core-members 23, in such manner that the outer ends of the coremembers project slightly above the outer side oi the spool. The coil 25 is electrically connected to a suitable amplifier and loude'speaker unit it by means of conductors 2d connecting the coil 2E6 to a jack 29 provided in the body, which is adapted to receive conductors extending from the amplifying unit 2?. A variable resistance volume control 30 and a tone control 3i may be provided in the instrument and interposed between the coil and amplifying unit, including respective control knobs 32 and 33 which project them conveniently accessible i'or manipulation by the player. 3-: r i.

The underside or bottom of the body iii is pro= insertion of the pick-up unit it for mounting within the body. This opening is normally covered by a closure plate 35 which may be attached to the body in any suitahle'inanner. The upper side of the body I0 is also'provided with an opening 3's" positioned underneath the strings i3 and extending transversely thereof. The opening 35 per-= mits the upper portion of the pick-up unit iii to extend therethrough.

. In the operation of the instrument, the strings iii being adjacent the mamiet Ill, are magnetized thereby. when set in vibration by the player, the magnetizedi strings induce a pulsating cur rent hrthe-coil .25;which-is amplified and trans-= formed by the amplifier and loud-speaker unit 22 into tones c'orrespondingto thoseproducedhy.

the vibrations oi.the strings; To increase the induction within'th'e coil, the coil-is'generally provided with a core and the electromotive force which is i'nduced in the coil by the .vibrations'of the strings varies withxthe. spacing between the strings and the'core; 'Theistrings'of the instru -I ment being conventionally of difierent diameters and'lying in a common plane would ordinarily provide air gaps between the strings and core' which would vary with the diameters of'the strings; To compensate for .this diflerence in spacing, the core of my present invention con' sists of a plurality of core-members 23-which are threaded into the pole-plate i8 of the magnet ll each core-member havingits notation of his choice with instrument to makeouter end facing 52,1?5,825 p one or the strings oi the instrument In this manner the core-members 23 are rendered adjustable for spacing relative to the strings to provide for the required air gap between each string and its respective core-member. The screw heads 24 on each of the core-members enables them to be readily raised or lowered with a screwdriver. The adjustability of the core-members also permits any desired variation in the air gap etween each member to either increase or decrease the pickup effect. The instrument may thus be voiced to produce desired tone-effects. It will thus be ob served that by means of the present invention the player may readily obtain the proper balance in the pick of the strings and the musical tuning or a minimum of effort.

Having described and illustrated the preferred embodiment oi my invention, I desire to be un derstood that I do not wish to limit mystelf to the specific form of my invention herein set forth, for it will be apparent to those skilled in the art that variations may be made in the details of con struction which will nevertheless fall within the scope of my invention asdefined in the appended claims.

Having thus described and illustrated my invention, what I claim as new and desire to secure by Letters Patent i. A pick-up unit for use in a stringed musical instrument having a plurality oi vibratory strings, comprising a permanent magnet having the end portion oi one of its pole-porti0ns disposed transversely of the strings, a plate mounted on said pole portion of the .magnet, said pole plate having a plurality of spaced threaded holes therein, a adjustably member having a face adjacent one of the strings and being individually adjustable ior spacing relative thereto, and an induction coil supported by 'said pole-plate and surrounding said core-memhers.

' 2. A pick-up unit for use in a stringed musical comprising a permanent magnet generally U- shaped in cross section, a plate mounted on a pole-portion of the magnet, a pole plate having a plurality of spaced, threaded holes therein, a plurality of threaded core members adjustably positioned in said holes, an induction coil supported by the pole plate and surrounding the several core members, and means for supporting the magnet, plate, core members andcoil as a unit beneath the general plane occupied by. the strings of the stringed instrument with the poles of the magnet'directedupwardiy towards and transversely of'the strings, and I members being respectively disposed adjacent to and in general alignment with the strings,

HERBERT S. SUNSHINE.

string and its corresponding coreplurality of threaded core-members positioned in said holes, each core with the several core 

